1. Field of the Invention
The present invention relates to reproducing audio-visual (AV) data recorded on a storage medium, and more particularly, to a storage medium storing metadata for providing an enhanced search function.
2. Related Art
Storage media, such as DVDs and Blu-ray discs (BDs), store audio-visual (AV) data composed of video, audio, and/or subtitles that are compression-encoded according to standards for digital video and audio compression, such as a MPEG (Motion Picture Experts Group) standard. Storage media also store additional information such as encoding properties of AV data or the order in which the AV data is to be reproduced. In general, moving pictures recorded on a storage medium are sequentially reproduced in a predetermined order. However, the moving pictures can be reproduced in units of chapters while AV data is being reproduced.
FIG. 1 illustrates a structure of AV data recorded on a typical storage medium. As shown in FIG. 1, a storage medium (such as the medium 250 shown, for example, in FIG. 2) is typically formed with multiple layers in order to manage a structure of AV data recorded thereon. The data structure 100 includes one or more clips 110 that are recording units of a multimedia image (AV data); one or more playlists 120 that are reproducing units of multimedia image (AV data); movie objects 130 including navigation commands that are used to reproduce a multimedia image (AV data); and an index table 140 that is used to specify a movie object to be first reproduced and titles of movie objects 130.
The clips 110 are implemented as one object which includes a clip AV stream 112 for an AV data stream for a high picture quality movie and clip information 114 for attributes corresponding to the AV data stream. For example, the AV data stream may be compressed according to a standard, such as the motion picture experts group (MPEG). However, such clips 110 need not require the AV data stream 112 to be compressed in all aspects of the present invention. In addition, the clip information 114 may include audio/video properties of the AV data stream 112, an entry point map in which information regarding a location of a randomly accessible entry point is recorded in units of a predetermined section and the like.
Each playlist 120 includes a playlist mark composed of marks which indicate the positions of clips 110 corresponding to the playlist 120. Each playlist 120 also includes a set of reproduction intervals of these clips 110, and each reproduction interval is referred to as a play item 122. Hence, the AV data can be reproduced in units of playlists 120 and in an order of play items 122 listed in each playlist 120.
The movie object 130 is formed with navigation command programs, and these navigation commands start reproduction of a playlist 120, switch between movie objects 130, or manage reproduction of a playlist 120 according to preference of a user.
The index table 140 is a table at the top layer of the storage medium to define a plurality of titles and menus, and includes start location information of all titles and menus such that a title or menu selected by a user operation, such as title search or menu call, can be reproduced. The index table 140 also includes start location information of a title or menu that is automatically reproduced first when a storage medium is placed on a reproducing apparatus.
However, in such a storage medium, there is no method for jumping to an arbitrary scene according to a search condition (e.g., scene, character, location, sound, or item) desired by a user and reproducing the scene. In other words, a typical storage medium does not provide a function for moving to a portion of the AV data according to a search condition (e.g., scene, character, location, sound, or item) set by the user and reproducing the portion. Therefore, the storage medium cannot offer diverse search functions.
Since AV data is compression-encoded and recorded on a conventional storage medium according to an MPEG 2 standard and multiplexed, it is difficult to manufacture a storage medium that contains metadata needed to search for a moving picture. In addition, once a storage medium is manufactured, it is almost impossible to edit or reuse AV data or metadata stored in the storage medium.
Further, a currently defined playlist mark cannot distinguish multiple angles or multiple paths. Therefore, even when AV data supports multiple angles or multiple paths, it is difficult to provide diverse enhanced search functions on the AV data.